Comparison of Knee Kinematics during
Anticipated and Unanticipated Landings
Tony Moreno PhD CSCS
School of Health Promotion and Human Performance
Eastern Michigan University
Overview
Basketball –
• In general, female high school participants incur knee injury
rates nearly twice as high as their male counterparts.
• Anterior cruciate ligament (ACL) injuries occur at a rate of
approximately 1 in 65 per participant annually.
• ACL surgery rate nearly 4 times higher.
Soccer –
• In general, female high school participants incur knee injury
rates approximately 2.5 times higher than their male
counterparts.
• ACL surgery rate 3 times higher
Hewett et al., 2006
Mechanism of Injury
Incidents are typically non-contact while the athlete is:
• landing from a jump or,
• conducting a pivoting or sidestep cutting-type
maneuver
Injury mechanism may involve:
• Tibial rotation in opposition to a femoral
rotation,
• concurrent with a valgus (knock-kneed)
stress at relatively low knee flexion angles,
• while suddenly decelerating on a fixed or
planted foot.
Statement of the Problem
Unpredictable landing and cutting movements are inherent
characteristics within sport, with knee joint flexion (KJF) and
time to peak knee joint flexion (TKJF) often associated with
increased risk of lower extremity injury.
– What kinematic differences exist between anticipated and
unanticipated jump landing conditions?
– Do injury prevention protocols address the indeterminate movement
conditions observed in practice and competition?
Purpose
The purpose of this study was to compare kinematic
parameters of the knee during anticipated and unanticipated
landing conditions among adolescent female basketball
athletes performing a maximal vertical jump effort.
Methods
• Six adolescent female AAU basketball players (13.8 ± 0.4yr.; 62.7 ±
17.87kg; 1.66 ± 0.08m).
• Maximal vertical jump assessed for all participants with the use of a
Vertec™ (Sports Imports, Columbus, OH).
• Participants performed a maximal vertical jump, landed and immediately
sprinted either left or right with an anticipated (A) and unanticipated (U)
direction upon impact.
Methods (continued)
• Kinematic data collected at 120 Hz with 8 digital cameras and EvART
Version 4.2 software (Falcon, Motion Analysis Corporation, Santa Rosa,
CA).
• Force data sampled at 1200Hz with an AMTI LG6 force platform (Advanced
Medical Technology Incorporated, Watertown, MA) synchronized with the
motion capture system.
• Kinetic data derived with MATLAB 7 software package (MathWorks,
Nattick, MA, USA).
• A paired sample t-test was performed for each dependent variable to
determine if significant differences (p< 0.05) existed between the
anticipated and unanticipated landing condition.
anticipated landing
unanticipated landing
Mean peak knee flexion
80
70.9
70
60
55.6
degrees
50
40
Anticipated
Unanticipated
30
20
10
0
KJF (A=70.9 ± 10.2º; U=55.6 ± 12.7º)
Mean time to peak knee flexion
0.21
0.2
0.2
seconds
0.19
Anticipated
0.18
Unanticipated
0.17
0.17
0.16
0.15
TKJF (A=0.2 ± 0.06s; U= 0.17 ± 0.05s)
Results
• Mean peak values for KJF (A=70.9 ± 10.2º; U=55.6 ± 12.7º) and
TKJF (A=0.2 ± 0.06s; U= 0.17 ± 0.05s) were significantly
different (p<0.05) when comparing anticipated to
unanticipated landing conditions.
• It is apparent subjects utilize different kinematic strategies
with the unpredictable landing scenario.
• Conclusion: Evaluation of anticipated and unanticipated
landings may be necessary to ensure injury intervention
protocols provide adequate variability and unpredictability to
attenuate factors associated with lower extremity injury.
Neuromuscular Factors
• Corrective responses via
proprioceptive (sensory)
feedback.
• Preplanning through the Central
Nervous System.
• Physical training can potentially
change the neuromuscular
response.
• Alteration of biomechanical
factors may reduce the incidence
or severity of injury.
Hewett et al., 2006
Mean peak knee extensor moment on impact
6
5.1
2
I x degrees/s /body mass(kg)
5
4
3
3.64
Anticipated
Unanticipated
2
1
0
PKJM (A= 3.64 ± 1.07 Nm/kg; U= 5.1 ± 1.4 Nm/kg)
anticipated training
unanticipated training
When comparing ACL injured subjects to controls
performing similar movements with video analysis…
- …injured demonstrate a hind or flatfoot disposition on impact
- …non-injured exhibit greater plantar flexion on impact
- …injured demonstrate less knee flexion on impact
Boden, et al. (20009)
Future Research
• Ankle joint kinematics (talar and subtalar) on landing, are
significantly associated with kinematic and kinetic measures
of the knee
–
–
–
–
–
–
Peak knee joint flexion
Time to peak knee joint flexion
Peak ground reaction force at impact
Eccentric knee extensor torques
Knee abduction/adduction torques
Relative loading rate at impact
These biomechanical parameters are strongly associated
with ACL and lower extremity injury…
Future Research
• Select uninjured population at risk for ACL injury and currently
participating in activities that include jumping and cutting.
• Determine the potential influence of ankle joint motion on knee joint
kinematics and kinetics, while landing from a jump task.
• Perform jump task with both anticipated and unanticipated landing
conditions.
• Expose experimental subjects to a training intervention (anticipated and
unanticipated?) that may alter proprioceptive mechanisms.
• To test the hypotheses, compare pre- and post intervention biomechanical
parameters within and between groups.
Thank You!
Tony Moreno PhD CSCS
School of Health Promotion and Human Performance
Eastern Michigan University
[email protected]